Fixing Wifi on the Eee PC 900: Part 2

My Eee PC has been humming along nicely for the past couple of months.  Things were going so smoothly that I didn’t have anything to write about.  That is, until now.  I just returned from a trip to San Jose, California.  I was preparing to catch up on my email while I watched the evening news and then it happened.  My Eee PC would no longer connect to my home network.

This problem was a quite different from the WiFi problem I wrote about previously.  In this case, my working configuration suddenly broke.  This is not susposed to happen.  There must be a good explanation but, I must find it first.

The first thing I noticed was that my Eee PC was not showing my Wireless access point on the wireless networks list.  Instead, the only network I could see was an unsecure network called Linksys.  Now it is not unusual for me to be able to see a neighbor’s access point but what was strange was I could not see mine.
I then decided to re-check the configuration file changes I made earlier to make the Eee PC connect in the first place.  The /etc/wpa_supplicant.conf_MINE file I generated appeared to be generic so I couldn’t imagine it was causing the problem.  The other file I made changes to was the /etc/network/interfaces file.  Below the portion of this file that deals with the connection to my wireless network.

iface lan2 inet manual
    down dhclient3 -r -pf /var/run/dhclient.$ -lf /var/run/dhclient.$IFACE.leases $IFACE
    down ifconfig $IFACE down
    up cp /etc/wpa_supplicant.conf_MINE /etc/wpa_supplicant.conf.ath0
    up wpa_cli -p /var/tmp/wpa_supplicant reconfigure
    up ifconfig $IFACE up
    up dhclient3 -cf /etc/dhcp3/dhclient.$LOGICAL.conf -pf /var/run/dhclient.$ -lf /var/run/dhclient.$IFACE.leases $IFACE
    wireless-channel 6
    wireless-essid Denkigai
    wireless-key bd8a577135194ff49b51b0602355b252ffd89827c07f477a659c498d0c1c93eb
    wireless-keymode open
    wireless-mode auto
    wireless-rate auto
    xncs-wireless-encryption wpa

Looking at the wireless configuration, my thought process went something like this:

  • I know the SSID of my wireless router did not change (it is still Denkigai)
  • I know the encryption type didn’t change (is is still WPA2-PSK)
  • I know the wireless key didn’t change (it is too long to type here again)
  • What else could have changed?  Doh, the wireless channel

 I brought up the diagnostic page from my wireless router and sure enough, it was now broadcasting on channel 1.  Light bulb moment!  I then realized that we had a power outage a couple of nights ago.  The router probably picked a new, presumably clear channel when it came up again.  I knew there was a good explanation.  I went ahead and edited the interfaces file and changed the wireless-channel to 1 and sure enough, the Eee PC connected.  I then wondered to myself why I specified the wireless channel at all.  I had no problem connecting to public hot-spots without specifying the channel.  So I did one final experiment and removed the wireless-channel line all together.  I restarted the PC and once again, it connected automatically.  Problem solved!

Moral of the story:  When setting up a wireless internet connection, do not specify a wireless channel unless you have a specific reason to do so.

Could a hard coded wireless channel explain the WiFi Problems on the Road incident?  Perhaps.

The Denki-Guy


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